Radioactivity And Particles

Question 1

Define Isotopes?

Answer 1

Same number of protons but different number of neutrons

Question 2

What is Radioactive decay

Answer 2

Nuclei of unstable isotope break down randomly

Question 3

Where does background nuclear radiation come from?

Answer 3

• Substances on Earth - air, food, building materials, soil, rocks
• Cosmic Rays
• Human activity - fallout of nuclear explosion or waste

Question 4

How does Nuclear Radiation cause Ionisation?

Answer 4

• By bashing into atoms + knocking electrons off them

* Atoms (no charge) turning into ions (charged) = ionisation

Question 5

How can something be Less Ionising?

Answer 5

Further radiation penetrates before hitting an atom + getting stopped, the less damage it will do along the way - less ionising

Question 6

How can Ionising Radiation be detected?

Answer 6

• Geiger Muller (GM) detector

* Photographic film

Question 7

What are the different types of Ionising Radiation?

Answer 7

• Alpha Particles
• Beta Particles
• Gamma Rays

Question 8

What are Alpha Particles?

Answer 8

• Helium nuclei
• 2 protons + neutrons
• Don’t penetrate far
• Big, heavy, slow moving
• Strongly ionising - bash into a lot of atoms+ knock off electrons before slow down = ions
• Deflected (direction changes) by electric + magnetic fields because positively charged

Question 9

What are Beta Particles?

Answer 9

• Electrons
• Fast moving, small
• Penetrate moderately before colliding + moderately ionising
• Negatively charged
• Deflected by electric + magnetic fields

Question 10

What are Gamma Rays?

Answer 10

• Short wavelength EM waves
• Penetrate far into materials
• Weakly ionising - pass through rather then collide with atoms
• No charge - not deflected by electric or magnetic fields

Question 11

When do Gamma Emissions happen?

Answer 11

After beta of alpha decay

Question 12

What is Alpha Particles penetrated by?

Answer 12

Blocked by paper, skin, few cm of air

Question 13

What is Beta Particles penetrated by?

Answer 13

Blocked by thin metal (aluminium )

Question 14

What is Gamma Rays penetrated by?

Answer 14

Blocked by thick lead or very thick concrete

Question 15

How can you Investigate the Penetration of Radiation?

Answer 15

•GM

Question 16

What does the GM detector do?

Answer 16

Gives a count rate - number of radioactive particles reaching it per second

Question 17

How can you Investigate the Penetration of Radiation?

Answer 17

• Attach radioactive source to material+GM detector+counter
• Remove source to measure background count over time period
• Divide count by time period to get background count per sec
• Repeat + find mean
• Replace source + measure count rate with no material + repeat + find mean
• Insert different material,record count,repeat
• If count rate remains same when material inserted - Radiation can penetrate the material

Question 18

How do you Prevent Radioactive Sources from being Dangerous?

Answer 18

• Keep then in lead-lined box
• Pick them up using long tongs
• Don’t point them at anyone, keep a safe distance from them

Question 19

What is the Alpha emission?

Answer 19

• Mass number decreases by 4

* Atomic number decreases by 2

Question 20

What is the Beta emission?

Answer 20

• Mass number stays the same

* Atomic number increases by 1

Question 21

What is the Gamma emission?

Answer 21

Mass and atomic number stays the same

Question 22

What is the Neutron emission?

Answer 22

• Mass number decreases by 1

* Atomic number stays the same